Holding and supporting device for printing or print-receiving elements or the like



July 3, 1928. 1,675,493

W. C. HUEBNER HOLDING AND SUPPORTING DEVICE FOR PRINTING OR ',PRIN'E--RECEIVING ELEMENTS OR THE LIKE Filed Nov. 8, 1924 4 Sheets-Sheet 1 iuly 3, 1928.

-W. C. HUEBNER HOLDING AND SUPPORTING DEVICE FOR PRINTING OR PRINT RECEIVING ELEMENTS OR THE LIKE Filed NOV. 1924 4 Sheets-Sheet HUEBNER HOLDING AND SUPPORTING DEVICE FOR PRINTING OR PRINT RECEIVING ELEMENTS OR THE LIKE Filed NOV 8, 1924 4 Sheets-Sheet 3 July 3, 1928. 'l',675,493

W. C. HUEBNER HOLDING AND SUPPORTING nEvIcE FOR PRINTING on PRINT RECEIVING ELEMENTS OR THE LIKE Filed Nov. 8, 1924 4 Sheets-Sheet 4 /0 .4 2/ 39 JZ v/ E Z I Ill Ii 4 35 E I Z0: I

: l .39 i i I 1 v I l v i E ATTOF/Vf/j Patented July 3, 1928.

UNITED sTATEs 1,675,493 PATENT OFFICE.

WILLIAM C. HUEBNEB OF BUFFALO,-NEW YORK, ASSIGNOR T HUEBNER-iBLEISTEIN PAT NTS COMPANY, OF BUFFALO, NEW YORK.

HOLDING AND SUPPORTING DEVICE FOR PRINTING on PRINT-RECEIVING minimums OR THE LIKE.

Application filed. November 8, 1924. Serial No. 748,594.

. This invention relates to holders and supports therefor upon which flexible sheets, films or the like, comprising printing or print-receiving elements are adapted to be 6 mounted for printing purposes, said holders having means whereby such sheets or films may be stretched and drawn taut thereon, and so as to enable an imageon such sheet to be accurately positioned in predetermined 10 location and registered as to size by the stretching of the sheet on the holder. A

holder of this sort is disclosed in my copending application for Letters Patent filed Oct. 10,1924, Serial No. 742,919, entitled Holding and supporting devices for printing or print receiving elements and the like.

This invention relates more particularly to an improved holder of this sort and supporting means therefor adapted especially for use on photographic printing apparatus, and in which a partial vacuum is created between the opposed faces of a flexible printing or other element and an opposed flexible element, each of which is mounted on a holder of the sort mentioned, so as to obtain close and uniform contact between said surfaces.

One object of the invention is to provide an improved holder of the sort mentioned and having a suction chamber in which a partial vacuum may be created to withdraw the air from between two contacting flexible elements or sheets each on a different holder, and to arrange the adjustable sheet securing and stretching devices in said chamber so that they will be disposed below or will not project beyond the surface of the sheet on the holder, but will nevertheless be easily accessible for manipulation to adjust or stretch the sheets on the holder. Other objects are to provide an improved support on which the holders are adapted to be detachably secured and which is provided with a plate member adapted to engage the edge portions of a: sheet or film mounted on a holder so as to extend outwardly around the sheet and form a surface which is coplanar therewith, whereby a flexible sheet mounted on another holder, when brought into enmay engage and have perfect contact therewith ;even though portions thereof extend beyond the edges of said sheet; also to construct the holders and the support so that gagement with the sheet on the first holder,

when such contactin sheet overlaps or extends beyond the first sheet, the suction chamber of the second holder will nevertheless be tightly sealed, in part by the plate member of the support and in part by the first sheet, so as to enable suction to beapplied in said suction chamber to withdraw the air from between opposed sheets and obtain perfect contact therebetween; also to construct a support having a plate member to which a holder is. adapted to be secured, said plate member being further adapted to act as a sealing member for the suction chamber of the holder, and also as a sealing member to seal the suction chamber of a holder for a flexible member adapted to contact with the sheet on the other holder.

Additional objects are to construct a supportv having a plurality of interchangeable plate members, each of which is adapted to removably-supporta holder of different size and to cooperate with a flexible sheet or element on the holder to form a coplanar surface therewith; also to provide improved means for detachably securing the plate members on the support in predetermined location and to provide means for detachably securing the holders on the plate members in predetermined location, and to construct the support so that the support itself may be secured in predetermined definite location with reference to a master or zero position ona photographic printing apparatus, whereby. a prlnting sheet or element mounted in predetermined position 'on a holder and support onanother part of the apparatus may be brought into contact with the first sheet to print an image thereon in predetermined position, or to print a plurality of like images in spaced relation all inpredetermined position on said sheet.

Still other objects are to improve holders of the sort mentioned on which flexible sheets are mounted, and the supports for mounted, andshowing a flexible sheet on another holder in contact with and overlapping the edges of the first sheet.

Fig. 3 is a rear elevation of the support wit-h a holder in place thereon.

Fig. 4 is a fragmentary face view of one of the holders.

Fig. 5 is a transverse section of the sup- I port and a holder with a flexible sheet mounted thereon arranged in contact with a sheet on another holder, said section being on line 55, Fig. 2, but on an enlarged scale.

Fig. 6 is a rear elevation of one of the positioning and securing devices for detachably securing the plate member on the sup port.

Fig. 7 is an enlarged sectional view showing a portion of the plate member ofthe sup port in operative position with reference to a flexible sheet on a holder.

Fig. 8 is a rear elevation of one of the positlonin and securing devices for detachably securing the holder on the support.

Fig. 9 is .a fragmentary face view of a holder on which a porous flexible sheet is mounted and showing a non-porous sheet used as a backing to seal the pores in the porous sheet.

Fig. 10 is a transverse sectional elevation on an enlarged scale on line 1O1(), Fig. 9.

Figs. 11 and 12 are a transverse sectional elevation and a fragmentary face View respectively of a holder on which a metal press plate is mounted.

A photographic printing apparatus of any construction adapting it to cooperate with the holders and supports of t e present invention may be employed. T e apparatus shown in Fig. 1 comprises a pair of swinging frames or carriers 10 and 11, pivotally supported on a fixed standard or post 12 so that either carrier may be moved towards the other. The carrier 10 comprises an open, rectangular frame, and a holder .A of the sort disclosed in said copending application is adapted to be detachably secured and accurately positioned in predetermined position on a support B constructed in accordance with the present invention, and which is removably attached in the frame 10. The other carrier 11 also includes an open frame on which a pair of horizontal spaced bars 13 are mounted for vertical adjustment thereon toward and from each other. A holder A like the holder A, isdetachably secured in predetermined position on a support B which, in turn is adapted to be accurately located in predetermined position on the carrier 11, by suitable means, such as dowels 14 passing through holes 15 in the support into any selected pair of holes 15 in the upper and lower bars 13. The holders A A and the support B are constructedsubstantially as disclosed in said copending application and will be briefly described to assist in a a rectangular frame 16 having a central aperture 17 and is provided with a wall or ledge 18 extending perpendicularly from the face of the frame around and adjacent the aperture 17. The ledge is faced with rubber or other resilient material 19 forming a compressible, raised support on which the edge portions of a flexible sheet C are adapted to bear. The sheet extends across the aperture 17 with its edges extending outwardly beyond the ledge 18, and the holder is provided with a plurality of movable and separably adjustable sheet-securing and stretching devices or clips 20 adapted to grip the edges of the sheet and to be adjusted to draw the sheet down on the facing 19 and stretch it taut and smooth over the frame aperture. Another wall or ledge 21 extends around the outer periphery of the frame and projects upwardly therefrom and has a rubher or analogous facing 22, the outer surface of which is substantially in the plane of the outer or top surface of the sheet C. The two ledges or walls 18 and 21 form with the frame 16 a continuous annular suction channel or chamber 24 extending around the holder, and in which the gripping devices.

or clips 20 are arranged so as not to project outwardly beyond the plane of the outer face of the sheet C, and so as to have limited movements on the frame toward and from the frame aperture and also transversely of such direction. Suction may be applied from any suitable source to create a partial vacuum in the chamber 24 when the holder is in use by means of a connection 24 to which a hose or the like can be attached. The connection 24 is secured at the back of the holder in a hole in the frame 16.

Each clip 20, see Figs. 4 and 5, includes two members 25, 26, having gripping .jaws 27, 28 respectively. The two members are pivotally connected as by a hinge pin 29 to permit the jaw 28 to move towards and from the other jaw. The jaws are opened and closed by means of levers 30 pivoted on one of the clip members and having cam faces engaging the other member so that when the levers are turnedin one direction they rock the member 26 to close the jaws and when turned in the opposite direction permit the jaw 28 to open. The member 25 of each clip is preferably arranged on the face of the frame 16 and the clips are slidably adjusted by screws 32 swivelled in slots in stationary bearings 33 disposed outwardly beyond the clips, each screw engaging in'a threaded hole in the member 25, so that by turning the screw the clip can be moved toward and from the frame aperture 17. Fixed retainers 34 having portions overhanging lateral lugs 35 at opposite ends of the clips limit the transverse sliding movements of the clips and prevent them from lifting or moving upwardly away from the frame. As will be seen from Fig. 5, the grip ing jaws 27 and 28 are inclined with ref and are disposed below or back of the outer face of the sheet C and of the ledge facing 19, so that when the clips are manipulated to tighten the sheet, the edge portions of the sheet will be drawn down against the facing and the sheet stretched taut and smooth over the .aperture 17, and as each device 20 is independently adjustable, they can be manipulated to apply greater or less .tension to different portions of the sheet as may be required.

The holder A, see Figs. 4 and 5, is of slightly difierent construction from the holder A, also shown in Fig. 5, in that the sheet gripping devices or slips 20 are supported on separate movable bars 38, one of which is disposed in the suction chamber 24 at each side of the frame aperture 17 The clips 20, adjusting devices 32, 33 and retainers 34 are arranged on the bars 38. The bars 38 are adapted to move on the frame toward and from the frame aperture so that a general adjustment or stretching of the sheet may be effected, as by means of adjusting screws39, the inner ends of which are sw-ivelled on the bars, while the screws have a screw-threaded engagement in threaded holes 41 in the outer ledges 21. By adjusting these screws 39, the bars 38 may be moved toward and from the frame aperture to quickly effect a general adjustment and stretching of the shee after which local adjustments thereof ma; be effected when necessary, by separately adjusting the appropriate clips 20 by ineans of the screws 32. In the other holder A, the clips 20 are mounted directly on the frame 16. The bars 38 may; however, be used on both holders A A, or entirel omitted as desired.

The supports upon which the holders A are secured comprise primary and secondary members 42, 43, the holder A having holes into which dowels on the member 43 are adapted to fit, to position the same in predetermined position on the support, and the holder is held in place by latches or fingers 44, see Fig. 1. The secondary member 43 is removably and adjustably secured on the primary member 42 by screw'clips 45, which are adapted to provide transverse movements in two directions of the member 43 on the member 42 and also hold the mem-' cation. The holders are thus adapted to be secured in predetermined position on the support 13, while the support, as stated, is also adapted to be secured in predetermined position on the printing apparatus by the erence to dowels 14. The holes 15 are spaced apart in definite units of measurement from opposite sides of the image position line y y.

In accordance with this invention, a support B is providedupon which any one of a plurality of plate members 48 is adapted to be placed and secured in definite predetermined position, these plate members being all of the same outer dimensions and form, but having different sized central apertures in or over which corresponding sizes of the holders A or A are adapted to be removably secured, also in definite predetermined relation, so that a flexible sheet or element C mounted and stretched on a holder as described may extend across and fill the opening in the plate member in such a way that said member will lie substantially flush or coplanar with the surface of the sheet. This sheet C, which may have an image thereon and is hereinafter called the printing element, when arranged in coplanar relation to the plate member as described, is adapted to contact face to face with a second sheet C which may be prepared with a photographic or light sensitive coating, and 1s hereinafter called the print-receiving element. The sheet G is moved into engagement face to face with the sheetC, see Figs. 2 and 5, to print an impression or series of impressions thereon in predetermined position, close contact' being secured by exhausting the air from between the sheets by applying suction in the chamber 24 of the holder A: In some of v such positions, the sheet C may overlap or follows-:-

The support B includes an open rectangular frame formed of connected, flat, relatively wide rails 46 arranged edgewise, which frame is adapted to fit and be secured in the opening of the swinging carrier 10 of the photographic printing apparatus, as by means of fasteningdevices 47 of any suitable sort, see Fig. 1. ach plate member before mentioned comprises a flat, rectangular metal plate 48 adapted to fit in'the opening in the frame 46 and has a central rectangular opening or aperture 49 over the back of which one of the holders A is removably secured so as to position the sheet C thereon across the opening. A number of the plates 48 are provided having different sized openings 49 therein corresponding to the different sizes of holders A and-sheets G used. In each case the aperture 49 is so formed that the edges of the plate will engage the edge portions of the sheet on the attached holder and bear on the top face thereof at or about the center of the resilient facing 19 of the a ledge 18 so that the portion of the sheet within this area is exposed through the aperture 49 and the remainder thereof, together with the suction chamber 24 and sheet securing clips .20 of the holder, will be beneath or back of the plate 48 with the resilient facing of the outer ledge 21 engaging therewith and sealing said chan'iber. Preferably, the top of the ledge 18 and the edge of the plate which engage the facing 19'are correspondingly bevelled, as shown in Figs. and 7, so that the edge portions of the sheet C may be forced against and compress the facing and form a seal without injuring the sheet, which together with the facing 22 will provide an airtight closure for the suction chamber 24. The holder A is preferably ren'lovably secured in predetermined position on, the plate 48 in the following manner. As shown in Figs. 3, 5 and 8, a pair of dowel pins or studs 50 extends perpendicularly from the rear face of the plate 48, one at each side of and adjacent the aperture 49. The pins 50 can be secured to the plate in any suitable manner, being shown attached to blocks or fittings 51 secured by screws or rivets to the plate 48. Each holder is provided on opposite edges with lugs 52 having holes in which the pins 50 are adapted to accurately fit. The lugs are X slipped over the studs with their front faces engaging and bearing on the blocks 51,

while their rear faces are adapted to be engaged by locking devices adapted to maintain the holder A in position onthe studs 50. These locking devices comprise fingers having sleeve portions 54 adapted to fit loosely over screw studs 55 extending rearwardly from the blocks 51, so that the fingers can swing on the studs 55 into engagement with the rear faces of lugs 52 and be locked in such position by thumb nuts 56. The studs are preferably arranged on a horizontal line passing through the center of the aperture 49 and holder A, as on the horizontal center line, see Fig. 3,

which corresponds to the master image position line 00-400 of the apparatus shown in Fig. 1, but while only two studs are necessary to thus position the holder, further means may be. necessary to press the holder firmly against the plate member. A suitable number of additional lugs 52, fingers 53 and locking nuts 56 are therefore provided at different points around the holder, but no studs are used with these additional devices.

Each plate member 48 is in turn adapted to be detaehably secured in predetermined position on the frame 46, and for this purpose devices similar to those used for securon the vertical center line of the plate and holder, said line corresponding with the image position, line g 1 of Fig. 1, and the plate is locked or releasably secured in thisposition by fingers 62 loosely arranged on the screw, studs 63 and bearing on the lugs 61. fingers 62 are provided at intervals at the edges of the plate 48 to hold the plate firmly 1n the construction shown, the

in place.

Additional lugs 61, blocks 59 and.

lugs 61 are formed on a rectangular reinforcing member .64-secured to the inner faces of the rails of the frame 46 and adapted, to stiffen and brace thefran'ie. The edge portions of the plates 48 extend outwardly over and rest on the face of the member 64 so as to provide a substantially light, tight joint between the plates 48 and the frame 46. lVhen the supports B are used in an apparatus of relatively large size, the plates 48 being then of considerable area, may be braced or stiffened to prevent buckling, as by means of angle bars or other bars 65 riveted thereto, as shown in Figs. 3, 5 and 6.

In some cases the flexible sheets used on the holders A A may be of paper or other porous material which will. allow air to pass through the sheet and prevent the suction from producing the desired close contact between the opposed sheets. come this difiiculty, a rubber sheet or blanket 70, see Figs. 9 and 10, may be arranged on the holder, as for instance the holder A, beneath or behind the sheet C, and stretched taut so. as to engage the sheet and seal the pores therein. F or this purpose the sheet C and rubber blanket 70 are notched or cut away at their edges as at 71, 72 respectively,

the 'notches on the sheet and blanket being alternated so that the sheet and blanket maybe engaged by alternate clips or gripping devices 20 of the holder. By this arrangement, both sheets may be equally granted to me Sept. 20, 1921. For instance,

a plate 73 of this kind having a light sensitlve coating thereon, on which it is-desired to print an impression from an image on the sheet C, may be arranged on the holder A mounted on the support B, see Figs. 11 and 12. The marginal reinforcements or attachin bars comprise two narrow bars or strips 74, 75 between which an edge of the plate is clamped by suitable bolts or the like connecting the bars. Ordinarily, two only of these reinforcements are necessary, and are arranged at opposite edges of the plate. A pair of stretcher bars 76 adapted to bear on the face of the holder within the suction chamber 24 at opposite sides of the aperture 17 are formed with shoulders 77 under which the outer edges of the reinforcements are adapted to engage and with undercut seats 78 adapted to receive bevelled inner edges 79 on the bar 75 in such a way that outward movement ofthe stretcher bars 7 6 will force this edge into said seat and draw the metal plate tightly across the frame. Screws 80 similar to the adjusting screws before mentioned, passing through threaded holes in the ledges 21 and swivelled in the bars 76 serve to draw the bars outwardly on the frame. When metal plates are used as just described, the plate members 48 of the support B are covered with a thin sheet of rubber or other similar material as at 81, adaptedto pass inwardly over the edges of the central aperture 49 and bear against the metal plate 73 to avoid metal contact, and'insure a tight seal between these members.

When flexible sheets or plates are used with the marginal reinforcements described, it is desirable that means be provided for enabling such sheet or plate to be placed in predetermined position relatively to the holder on which it is used. For this purpose the marginal reinforcements or bars,

and the stretcher bars 76 are provided with interfitting parts adapting the reinforcing bars to occupy a predetermined position when placing the sheet on the holder, so that the sheet will be in the same predetermined location each time it is placed on the holder.

In the construction illustrated eachreinforcing bar is formed with a V-shaped tooth or projection 82 adapted to enter a corresponding recess 83 on one of the stretcher bars, and the stretcher bar in turn has an index mark 84 adapted to register with an index mark 85 on the bar 74 so that the sheet will be positioned in exactly the required location on the holder.

I claim as my invention:

1. In a printing apparatus, the combina-. .tion"of a support including a metal plate having an aperture therein, sheet holding means mounted on said support at one face of said plate and including holding parts extending into said aperture in position to hold a flexible sheet so as to extend across said aperture with its face substantially coplanar with the opposite face of said metal plate. q j

2. In a printing apparatus, the combination of a support including a framefa pluopposite face of said plate rality of metal plate members and means for securlng either of said plate members on said frame, each of said plates having an aperture of different size, and a plurality of sheet holders each adapted in size to a different size aperture and adapted to be secured on one face of a plate member having an aperture of corresponding size and each including holding parts extending into said aperture in position to hold a flexible sheet so that it will extend across said aperture with its surface substantially coplanar with the member.

3. In a printing apparatus, the combination of a support including a metal plate having an aperture therein, sheet holding means mounted on said support at one face of said plate and including holding parts extending into said aperture in position to hold a flexible sheet so as to extend across said aperture with its face substantially coplanar with the opposite face of said metal plate, and means on which a second flexible sheet is adapted to be held in close contact with said coplanar surfaces of said plate and said first sheet.

4. In a printing apparatus, the combination of a metal plate having an aperture therein, a sheet holder attached to one face of said plate and including holding parts extending into said opening in position to hold a flexible sheet so as to extend across and close said opening and with its outer surface substantially co-planar with the opposite face of said metal plate, and a second sheet holder on which another sheet is adapted to be held with its face in contact with said co-planar surface of said plate and first-sheet.

5. In a printing apparatus, the combination of a support including a metal plate having an aperture therein, sheet holding means attached to one face of said plate and including holding parts extending into Said opening in position to hold a flexible sheet with its edge. portions engaging the edges of said aperture and the portions of the sheet within said edges disposed across said aperture so as to extend with one surface in co-planar relation with the opposite face of said metal plate.

6. In a printing apparatus, the combination of -a metal plate having an aperture therein, a holder attached to one side of said plate and having an opening over which a flexible sheet is adapted to be vstretched, a ledge on said holder surrounding said opening and having a resilient facing, said sheet being adapted to extend across and close the aperture in said metal plate with its outer face extending in co-planar relation with the other side of said plate and with its edge portions bearing on said resilient facing and adapted to be engaged by the edges of the metal plate adjacent the aperture therein to press the same against said facing to seal the joint between said plate and sheet.

7.In a printing apparatus, the combination of a metal plate having an aperture therein, a holder attached to one side of said plate and adapted to hold a flexible sheet so as to extend across and close said aperture and with its outer surface co-planar with the other side of said metal plate, and a second holder on which another sheet is adapted to be held with its face in contact with said co-planar surfaces of, said plate and first sheet, said second holder having a suction chamber into which the edges of the sheet thereon extend, said chamber being adapted to be sealed against the entrance of air by said co-planar surfaces of said metal plate and first sheet, and means for exhausting air from said chamber to withdraw air from between said contacting surfaces. 8. In a printing apparatus, the combination of a metal plate having an aperture therein, a holder attached to one side of said plate and adapted to hold a flexible sheet so as to extend across and close said aperture and with its outer surface oo-planar with the other side of said metal plate, and a second holder on which another sheet is adapted to be held with its face in contact with said co-planar surfaces of said plate and first sheet, said second holder having a suction chamber into which the edges of the sheet thereon extend, means for sealing said chamber against the entrance of air while permitting communication between said chamber and the air space between said contacting surfaces, and a suction connection on said second holder for exhausting air from said chamber to withdraw air from between said contacting surfaces.

9. In a printing apparatus, the combination of a metal plate having an aperture therein, a holder attached to one side of said plate and adapted to hold a flexible sheet so as to extend across and close said aperture and with its outer surface coplanar with the other side of said metal plate, and a second holder on which another sheet is adapted tobe held with its face in contact with said coplanar surfaces of said plate and first sheet, said second holder having a suction chamber into which the edges of the sheet thereon extend, a suction connection on said second holder for exhausting air from said chamber to withdraw air from between said contacting surfaces, and said suction chamber being adapted to be sealed against the outside atmosphere in part by said metal plate and in part by said first mentioned flexible. sheet.

10. A printing apparatus comprising a holder for a flexible sheet, said holder having an opening, an open sided chamber in said holder surrounding said opening, sheet securing devices arranged in said chamber and adapted to engage the edges of said sheet and draw the same taut over said opening, said holder being adapted to be positioned to engage said sheet with another sheet extending beyond the edges of said first sheet, said second sheet being adapted to seal said chamber, and a suction connection on said holder for exhausting air from said chamber to withdraw air from between said sheets to obtain close contact therebetween.

11. In a printing apparatus the combination of a metal plate having an aperture therein, means for holding a flexible sheet across said aperture at one side of said plate and so as to engage the edges of said aperture, means for holding another flexible sheet across. said opening at the other side of said plate in engagement face to face with said first sheet, said second holding means having a suction chamber surrounding the sheet thereon and in communication with the air space between said engaging sheets, and a suction connection with said chamber for withdrawing air therefrom and from between said sheets to obtain close contact therebetween.

12. In a printing apparatus the combination of a metal plate having an aperture therein, means for-holding a flexible sheet across said aperture at one side of said plate and so as to engage the edges of said aperture, a holder for a second flexible sheet at the opposite side of said plate and having an opening therein, a suction chamber in said holder surrounding the sheet thereoii, securing devices in said suction chamber adapted to engage the edges of the sheet and stretch the same across said opening, said holder being adapted to support said second sheet in engagement face to face with said first sheet, and a suction connection with said chamber to withdraw air therefrom and from between saidsheets to obtain close contact therebetween.

13. In a printing apparatus the combination of a metal plate having an aperture therein, a holder attached to one side of said plate and adapted to hold a flexible sheet so as to extend across and close said aperture and with its outer surface co-planar with the other side of said metal plate, a holder for a second sheet and having an opening therein, a yielding ledge surrounding said opening, securing devices arranged on said holder outwardly beyond said ledge and back of the plane of the face-thereof, said securing devices being-adapted to engage the edges of said second sheet and draw the sheet against said ledge and stretch it over said opening, a second yielding ledge on said holder outwardly beyond the first ledge and forming therewith a suction chamber extending around said opening, said holder being adapted to be positioned to engage the second sheet face to face with the a flexible sheet thereon and including parts extending into said aperture in position to support said sheet over sald aperture so as to extend with the corresponding surfaces of said sheet and plate in substantially coplanar relation, and means for releasably securing said holder in predetermined position on said metal plate.

15. In a holding and supporting device for a flexible image bearing sheet and adapted for use in a printing apparatus having a predetermined image posit-ion, a metal plate having an aperture therein, a holder on which said image bearing sheet is adapted to be mounted and which is arranged to support said sheet so as to extend across said aperture in co-planar relation to the surface of said plate, means for adjusting the image on said sheet relatively to said holder, means for releasably securing said holder in predetermined position on saidmet-al plate, and means for securing said metal plate in predetermined position on said apparatus to locate said adjusted image in predetermined relation to said image position thereon.

16. In a printing apparatus, the combination of a metal plate having an aperture therein, holder having means. for securing a flexible sheet thereon and arranged to support said sheet over said aperture so as to extend in co-planar relation to one face of said plate, parts on the opposite face of said metal plateadapted to'engage complementary parts on said holder to position the holder in predetermined relation to said plate, and securing devices for releasably retaining said holder on said plate.

17. In a printing apparatus, the combination of a metal plate having an aperture therein, a holder having means for securing a flexible sheet thereon and arranged to support said sheet over said aperture so as to extend in coplanar relation to one face of said plate, adjusting devices on said holder adapted to adjust the image. on said sheet relatively to said holder, parts on the opposite face of said metal plate adapted to engage complementary parts on said holder to position said adjusted image in predetermined relation to said metal plate, and securing devices for releasably retaining said holder on said plate.

18. In a printing apparatus, the combination of a support including a rectangular open frame, a rectangular metal plate adapted to substantially cover the opening in said frame and having an aperture therein, a holder having means for securing a flexible sheet thereon and arranged to support said sheet over said aperture so as to extend in co-planar relation to one face of said plate, means for adjusting the image on said sheet relatively to said holder, means for securing the holder in predetern'iined position on the opposite face of said metal plate, and means for securing said metal plate in predetermined position on said f 'ame.

19. In a printing apparatus, the combination of a support including a rectangular open frame, a rectangular metal plate adapted to substantially cover theopening in said frame and having an aperture therein, a holder having means for securing a flexible sheet thereon and adapted to support said sheet over said aperture so as to extend in coplaner relation to the surface of said plate, means for adjusting the image on. said sheet relatively to said holder, parts on said metal plate adapted to engage complementary parts on said holder to position the holder in predetermined relation to said plate, securing devices for releasably retaining said holder on said plate, parts on said plate adapted to engage complementary parts on said frame to position the plate in predetermined relation to said frame, and securing devices for releasably securing said plate in position on said frame.

20. In a holding and supporting'device for a flexible image bearing sheet and adapted for use on a printing apparatus having a predetermined image position, the combination of a support including a rectangular frame, a rectangular metal plate .face of said metal plate, means for securing 1 said metal plate in predetermined position on said frame, and means for securing said support in predetermined position on said apparatus to locate said image in predetermined relation to said image position thereon.

21. A holder for a flexible sheet or film comprising a frame having an opening,'an open sided chamber in said holder surrounding said opening, a plurality ,of adjustable sheet securing devices arranged in said chamber and adapted to engage the edges of said sheet to draw the same taut over said opening, stretching bars in said chamber at opposite sides of saidopening and on which said securing devices are movably mounted, means on the frame engaging said bars to shift the same together with said securing devices relatively to said frame. and means for independently adjusting said securing devices to shift them relatively to said stretching bars.

22. A holder for a flexible sheet or film having reinforcing members secured at the edges thereof, said holder comprising a frame having an opening, an open sided chamber in said holder surrounding said opening, stretcher bars arranged in said chamber and having parts adapted to'releasably retain said sheet reinforcing members, lnterfittlng parts on said stretcher bars and reinforcing members for positioningon said holder.

WILLIAM C. HUEBNER. 

